The present disclosure relates to a reproducing apparatus applied to reproduce an optical medium such as an optical disk, and a reproducing method.
For example, when reproducing a multilayer optical disk, there are high possibilities that a signal light amount reduces and an error occurs while reading a signal. There is a homodyne detection system that amplifies a detection signal using light interference (refer to Japanese Unexamined Patent Application Publication No. 2008-269680 and Japanese Unexamined Patent Application Publication No. 2008-65961).
In Japanese Unexamined Patent Application Publication No. 2008-269680 or Japanese Unexamined Patent Application Publication No. 2008-65961, it is designed to detect four groups, the phase differences of which differ by 90°, of signal light beams and reference light beams, as a homodyne system of detecting light, in which the signal light interferes with the reference light. Specifically, the groups, the phase differences of which are respectively set as 0°, 90°, 180°, and 270°, of the signal light beams and the reference light beams are respectively detected. Each detecting is performed by detecting light intensity in regard to the light in which the signal light interferes with the reference light.
Furthermore, Japanese Unexamined Patent Application Publication No. 2013-54801 discloses a reproducing apparatus by which it is possible to improve SNR of a reproduction signal compared to the apparatus using the homodyne detection method in the related art.